Railroad signaling system.



H. BEZER.

RAILROAD SIGNALING SYSTEM.

APPLICATION FILED 111115 10. 1910.,

Patented Apr. 3,1917.

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RAILROAD SIGNALING SYSTEM.

APPLICATION FILED JUNE 10. 1910.

Patented Apr. 3, 1917.

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APPLICATION FILED JUNE I0. 1910- Patented Apr. 3,1917.

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RAILROAD SIGNAHNG SYSTEM.

APPLICAHON FILED JUNE 10. 1910.

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Patented Apr. 3,1917.

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RAILROAD SIGNAUNG SYSTEM.

APPLICATION FILED JUNE 10. 1910'."

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RAILROAD SIGNALING SYSTEM.

APPLICATION FILED JUNE 10. 1910- LQQLUT? Patented Apr. 3, 1917.

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APPLICATION FILED JUNE 10. 19H).

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HENRY BEZER, OF NEWARK, NEW JERSEY.

RAILROAD SIGNALING SYSTEM.

Specification of Letters Patent.

Patented Apr. 3, 1917.

Application filed. June 10, 1916. Serial No. 566,138.

To all whom it may concern:

Be it known that l, HENRY Bnznn, a subjoct of the Crown of Great Britain, and a resident of Newark, county of Essex, and State of New Jersey, have invented certain new and useful improvements in Railroad Signaling Systems, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof.

This invention relates to that class of electrical signaling apparatus and systems in which the track is a part of the circuit containing the instruments which control the signals, the train itself controlling the operation of the signals by short circuiting or shunting the current in such track circuit.

It is common knowledge that foreign currents from various sources enter the rails and often seriously interfere with the proper working of the instruments, and it is the main object of my present invention to provide protection against such foreign current interference. I attain this by so arranging the system and devising the instruments that the latter will only respond effectively to currents or current impulses of such a nature as are not likely to be produced other than by the special means which ll provide for producing them. That is to say, I provide for initially producing at the proper time, a group of current impulses of a peculiar and predetermined nature such as are not likely to be found in, or produced by, a foreign current, and I provide signal controlling means such as will respond only to such a group of current impulses. This eliminates one of the gravest sources of danger in con nection with electric signaling apparatus of the present day, particularly in view of the heavy currents, which are constantly traversing the earth for light and power purposes often in close proximity to the rail road tracks.

I will now proceed to describe certain embodiments of my invention, having reference to the accompanying drawings in which the said embodiments are diagrammatically illustrated, and will then proceed to point out the novel features in claims.

In the drawings:

Figure l is a diagrammatic illustration of a normal clear system showing the instruments and circuits in their positions and condition immediately upon a train leaving a block and after. the track relay only has operated as a result of the first pulse in the track circuit.

Fig. 9. is a similar view showing the instruments and circuits in the positions and condition resulting from the second pulse and immediately before the third pulse in the track circuit.

Fig. 3 is a similar view showing the instruments and circuits in the positions and condition resulting from the third pulse and immediately before the fourth pulse in the track circuit.

is a similar view showing the instruments and circuits in the positions and condition resulting from the fourth pulse and by which the signal circuit is finally completed, the home signal guarding the block which the train has just left being set to its clear position.

F 5 is a detail view of the completed signal circuit as it appears in F ig. 4:.

Fig. 6 is a detail view of the line circuit in its normally uncompleted condition and showing in dotted lines how this circuit is te uporarily completed as a result of the second pulse in the track circuit. 7

Fig. 7 is a detail view of a local circuit established as a result of the first pulse in the track circuit.

Fig. 8 is a detail view of a local circuit established as a result of the second pulse in the track circuit, the same being found among the circuits illustrated in Fig. 2.

Fig. 9 is a detail view of a local circuit established as a result of the second pulse in the track circuit and continued as a result of the third pulse therein. This circuit will also be found among the circuits illustrated in Figs. 2 and 3.

Fig. 10 is a detail view of a local circuit, resulting from the third pulse in the track circuit. This circuit will also be found in Fig. 3.

Fig. 11 is a detail view of a line circuit resulting from the third pulse in the track circuit. This circuit will also be found in Fig. 3.

Fig. 12 is a detail view of another local circuit resulting from the third pulse in the track circuit. This circuit will also be found in Fig. 3.

Fig. 13 is a detail view of a local circuit established as a result of the fourth pulse. This circuit will also be found in Fig. 4.

Fig, 14 is a diagrammatic view of a system constituting another embodiment of my invention. I

Fig. 15 is a similar view showing the instruments in other positions and with different circuits established.

. I will describe an embodiment of my invention as applied to a system in which the signals are normally clear but are to move to the danger position immediately behind the trainfand later-return to a clear position as the train reaches some predetermined position farther along the line.

7' Referring first of all to Fig. 1 of the drawings, -21 designates the rails of a track of whicha full blockB is shown and portions of two other blocks A and G to the .rear and in advance thereof respectively.

22'23 are respectively the home and distantsignals at the beginning of the block '13, and 2425 are the home and distant signals respectively at the beginning of the block 0. I

The track circuit for the block B includes the rails 2021, wires 26 and 27 leading therefrom at the exit end of the block through a track battery 29'to contacts 30 31 of the pole'changing armature of a line 7 relay 28, and wires 3233 leading therefrom respectively at the entry end of the block, to and through the coils of a polarized track relay 34. .The wires 26-27 are provided j with branches leading to the coils of a shunt I relay 35, the same being therefore inparallel relation with the'track circuit and deriving energy in common therewith from the track battery 29. The coils of the line relay 28derive their energy from a line generator 36,.and the circuit therefor may be traced as follows, (see Fig. .4 or detail Fig. 6): Starting from the positive side .of the generator 36, a wire 37 leads to the contacts of a pole changer 38 mechanically operated by "and upon themovement of the home signal 24, thence through a wire 39 to the'eommon line-wire 40, thence through a wire 41 to a contact 42 closed at the proper time by the movement of the neutral armature of the polarized track relay 34, thence through a wire 43 to a contact 44 closed at the proper V timeby the armature of a second line relay coils of the line relay 28, and thence through a wire'51 back to the negative side of the I generator 36.

In addition to the line relays 28 and 45, the polarized track relay 34, and the shunt relay 35, there are three local relays 52,53, 54 the circuits for the coils of which, and the circuits which the said relays control, will be presently described. For the present it is sufficient to note that the coils are energized at the proper time by a generator 55 corresponding to the generator 36, which generator 55 acts also as a source of current foroperating the home and distant signals 22-23, and as a line generator for the circuits for line relays for the block A corresponding to the line relays 28, 45, which have been just described in connection with the block B. Similarly, the generator 36 acts as a source of power for operating the home and distant signals 24, 25, and likewise acts as a source of power for local relays for the block C such as will correspond to the local relays 52, 53, 54 employed in connection with the block B.

In Fig. 1 the various instruments are shown in the respective position they will assume immediately after a train has left the block B and entered the block C. In this connection, it may be noted that when the train entered the block B from the block A, the polarized armature of the track relay 34 was in the opposite position in which it is shown in this figure, thereby closing the contact 56, the contact 57 being thus open. When the train thus entered the block B, its wheels and axles by bridging the rails 20-21 shunted the coils of the polarized track relay 34, and caused them to drop their neutral armature, thereby opening the contact 42. This opened the line circuit above described, and caused the coils of the line relays 28, 45 to drop their armatures. The dropping of the armature of the line relay 45 operates to open the circuits for the signals 22, 23 thereby causing them to go to danger. The circuits for this will be hereafter described in their logical order. As the train approaches the end of the block B and just prior to its entry into the block C, it will shunt the coils of the shunt relay 35 thereby causing the armature thereof to drop and to open circuit at the contact 49. This makes a second break in the line circuit having therein the line relays 28 and 45, the other break being at the point 42 as just described. This second break is of substantially no consequence when the train is running in the direction just stated, but if it should so happen that the train were to back on to the block B from the block C, then the function of the shunt relay would be important because it would positively open the line circuit at this point when it might not be effected at the point 42 unless the train backed up to a considerable distance toward the entry end of the block B,-perhaps right up to the first rail therein. This is, of course, owing to the possible existence of track defects, and therefore possible action of foreign current. These track defects may consist of a broken rail, broken bond wires, etc, which would produce a difference in potential between one line of rails and the other line of rails, in a block, in case foreign current enters one or both lines of rails, and current would therefore flow through the track relay connecting the two lines of rails.

Now returning to the train which is in immediate proximity to the exit end of the block B, having reached he block B from the block A, it will be seen that the instruments are just as they are shown in Flg. 1 except that the neutral armature of the polarized track relay 34 has dropped, the polarized armature of the same instrument is in its opposite position, i. c. with the point 56 closed, and the armature of the shunt relay has dropped. Now as the train leaves the block B and passes wholly into the block C, the track battery 29 will energize the coils of the shunt relay 35 and the coils of the polarized relay 34, whereby their respective armatures will be attracted, and the points 49, 42 will be closed. At the same time the direction of the current through the track circuit in which the coils of the track relay 34 are contained is such as to cause the polarized armature of the relay 34 to be thrown to its opposite direction; 71. e. in the position in which it is shown in Fig. 1, thereby to open circuit at the point 56 and close circuit at the point 57. The instruments are now just as they are shown in Fig. 1, reference character 58 designating diagrammatically the presence of the train in the block C.

The train having reached this point, it will, of course, be understood that the home signal 22 is to be moved to its oblique or clear position and this is efiected by the means and in the manner which I will now describe. The final position of the several instruments necessary to bring about this result is with the armature of the line relay 45 attracted, the polarized armature of the track relay 34 moved over to the right,i. e. in a position to close circuit through the contact 56, and its neutral armature attracted and the armature of the local relay 54 in its position away from the coils thereof, such being the position of the parts as they appear in Fig. 4, the circuits for the signal 22 being then completed as follows, (see Fig. 4 and detail Fig. 5)

Starting from the positive side of the generator or battery 55, the circuit maybe traced through a wire 59 to the signal 22, thence through a wire 60 to a contact point 61 closed by the armature of the local relay 54 when in its rearward position, thence through a wire 62 to a contact 63 closed by the armature of the line relay 45, thence through a wire 64 to the contact 56, thence through a wire 65 back to the negative side of the generator 55. To bring about this condition of the various instruments, it is, however, necessary to produce three current reversals in the track circuit beyond that which was produced therein when the train entered the block C from the block B, by which the polarized armature of the track relay 34 was moved over to its position to close the contact 57. In other words, four pulses must be produced in this track circuit, each pulse being preferably, as herein shown, in the opposite direction to the preceding pulse, and responsive action must be had to these pulses in succession by the various instruments in the system before the signal can be moved to its clear position.

The first pulse having been produced as just stated, by the movement of the polarized armature of the track relay 34 to its position to close the contact 57, a circuit is established as follows, (see'Fig. 1 and detail view Fig. 7): Starting from the positive side of the generator 55, the current flows through portion of the wire 59, thence through a wire 66 to a contact point 67 controlled by the armature of the local relay 53, thence through a wire 68 to a circuit closer connected to the polarized armature of the track relay 34, thence through the contact 57 and a wire 69 to a contact point 70 controlled by the armature of the local relay 52, thence through a wire 71 to one of the coils 72 of the local relay 52, and thence through a wire 7 3, and a portion of the wire 65 back to the negative side of the generator 55. It may be noted that there is a normally closed local circuit through both of the coils 72-74 of the local relay 52, the same being traced through a branch wire 75 leading from the generator via the wire 66 to the coils 74, thence through a wire 76 to the wire 71 and thence through the coils 72 back to the generator. The closing of the circuit through the contacts 67 and 57 will have the effect of shunting the coils 74 whereby the armature of this relay will be immediately attracted toward .the coils 72. The result ofthis will be to break circuit at the point 70 whereby to open the last said circuit and thus to reestablish the local circuit for both the coils. The armature, however, being nearer the coils 72, will be held in this position by the action of the said local circuit.

The effect of moving the said armature of the local relay 52 toward the coils 72 is not only to break circuit at the point 70, but also to close circuit through contact points 77 and 78. The circuit closed through the contact point 78 is a line circuit including the line relay 28 thereby causing the coils thereof to attract their pole changing armature, and by this means the direction of current through the track circuit will be reversed thereby producing the second of the required group of pulses therein. The

55 V 1 the track circuit and causing the position ofthe polarized armature of the track relay said circuit may be traced as follows, reference be ng had to Fig. 2 of thedrawings which shows the lnstruments in this second position and to Fig. 6 which shows the circuit in detail: starting. from the positive side of the generator 36 thence through the wire 37 and pole changer 38, wire 39, common line wire 40 and wire 41, thence through a branch wire 89 leading from the r presently appear), thenc'e through a wire wire 41,'to'the contact 7 8, thence through a wire7 9 to acontact 80, (at this time, however, stillclosed as is shown in Figs. land 6;. and not open as is shown in Fig. 2, the latter condition resulting from the closing of the circuit nowbeing described as will 81 back to the wire 47, thence through the pole changer. 38, wire 48, contact 49, wire 50, coilsof the'line relay 28 and wire 51 back to the generator 36. The closing Iofthe contact ,78 will thus close line circuit for the line relay 28 as just above stated, but it Q will be noted that the coils of the line relay 45 are not included in this circuit. The reversalof current in the track circuit thus produced as the second pulse will effect a traced through a portion of the wire 59,

thence through a portion of the wire 66, thence through a wire 82 to a contact point 77. The contact point 77, it will be remembered, was closed at the same time the point 78 was closed, and the point 70 was opened upon the movement of the armature of the local relay 52 toward the coils 72 and in which position it is shown in Fig. 2. Thence the current flows through a wire 83 to the coils of the local relay 53, thence through a wire 84 to a back contact 85 controlled by the armature of the line relay 45, thence through the wire 64 to the contact 56 and 7 thence through the wire 65 back to the generator 55. Immediately this circuit is closed the coils of the relay 53 attract their armature and so break the previous line circuit at the point 80. This will cause the line relay 28 to drop its armature and so to again reverse the direction of current in the track circuit, producing the third pulse in r 34 to be again reversed, thereby opening the contact 56 and closing the contact 57, as is shownin Fig. 3. The opening of the conftact'56 would, of course, break the circuit just described for the coils of the local relay 53, but upon theattra'ction of the armature of the saidrelay, a local circuit was established therefor, in series with the'coils 72 of the local relay 52, through a contact point 87 as follows, (see detail Fig. 9) Starting again from the positive side of the generator 55, the circuit may be traced through parts of the wires 59 and 66, thence through the wire 82 to the contact 77 thence through the wire 83 and the coils of the relay 53, thence through a wire 86 to a contact point 87, thence through a wire 88 to the coils 72 of the local relay 52, and thence through the wire 73 and a portion of the wire back to the generator 55. The local circuit thus established is through the coils of the relay 53 in series with the coils 72 of the relay 52, and the armature of the coils 53 is held in its attracted position.

The result of closing the contact 57 by the third pulse just described is to close a circuit for the coils'of the local relay 54, which circuit may be traced as follows, reference being had to Figs. 3 and 10 of the drawings: commencing with the positive side of the generator 55, through portions of the wires 5966, thence through the wire 82 to the contact 77, thence through the wire 83, down through a branch wire 90 to the coils of the local relay 54, thence through wires 9192 to the wire 69, thence through the wire 69 to the contact 57 of the track relay 34, thence through the wire 68 to a contact 93 controlled by the armature of the local relay 53, thence through a wire 94 to the wire 65 and thence by way of a portion of the wire 65 back to the generator. The 10- cal relay 54 is thus in a condition to attract its armature as is shown in Fig. 3, and in so doing it closes a line circuit which includes the coils of both the line relays 28 and 45, as follows, (see also Fig. 11) starting from the positive side of the generator 36, thence through the wire 37 to the pole changer 38, thence through the wire 39 to the common line wire 40, thence through a portion of the wire 41 to the wire 89, thence through the wire 89 to the contact 78, thence through a portion of the wire 7 9 down through a wire 95 to a contact 96 controlled by the armature of the local relay 54, thence through a wire 97 to the wire 46, thence through a portion of the wire 46 to the coils of the second line relay 45, thence by the line wire 47 back to the pole changer 38, thence by the wire 48 to the contact 49 of the shunt relay 35, thence by the wire 50 to the coils of the first line relay 28, and thence by the wire 51 back to the generator 36. The result of the closing of this circuit is three fold :First, it causes the coils of the line relay 28 to attract their armature to thereby again reverse the direction of the current in the track circuit, to thereby eifect the fourth pulse therein; second, it causes the coils of the second line relay 45 to attract their neutral armature; third, because of the direction of the current through the line circuit and hence through the coils of the second line relay 45, it causes a reversal of the position of the polarized armature thereof, moving it to the position shown in Fig. 3. The reversal of the direction of the current of the track circuit e. the fourth pulse therein, as just described) causes a reversal of the position of the polarized armature of the track relay 34, thereby causing the said armature to again close the contact 56 and open the contact 57 as shown in Fig. 4.

The opening of the contact 57 in the track relay v34 would of course break the circuit just described for the coils of the local relay 54, but upon the attraction of the armature of the said relay, a local circuit was established via its own contact 112- in series with the coils 72 of the local relay 52.

This circuit is shown in Figs. 3 and 12 and is in parallel with a similar circuit previously described for the coils 53 and shown in Fig. 9, but it must be borne in mind that the contact 57 in the relay 34 is now open. By these circuits the coils 53 and 54 for the present hold their armatures.

The circuit for the coils 53 has been already described by reference to Fig. 9, that for the coils 54 is as follows :starting from the positive side of the generator 55, thence through portions of the wires 59 and 66, thence through the wire 82 to the contact 77, thence through the wires 83 and 90 to the coils of the relay 54, thence through the wire 91 to the contact 112, thence through the wires 113 and 88 to the coils 72 of the relay 52, and thence through the wire 73 and a portion of the wire 65 back to the generator 55.

At this instant coil 74, relay 53 and relay 54 are in multiple with each other and in series with coil 72. This multiple circuit is clearly shown in Fig. 12, bearing in mind that the contact 57 in the relay 34 is now open instead of being closed, as shown in Fig. 12.

It may be noted here that every time the direction of the current through the coils of the polarized track relay 34 was reversed in the production of a new pulse, the neutra l armature of the said relay would be momentarily dropped, but immediately picked up again. Up to this time the opening or closing of the circuits controlled by the neutral armature of this relay was immaterial, but at this period in the operation of the system the closing of the contact points controlled thereby is material as will now be shown. There are two contact points closed,one the contact point 42 which has already been described, and the other a contact point 98. The closing of the contact 42 establishes a line circuit having two multiple branches, one being through contacts 42 and 44 and the other through contacts 78 and 96, so that the line circuit will be maintained through the branch containing the points 42 and 44 when the other branch through the contact point 78 is broken. The closing of the contact 98 completes a new circuit consisting of a circuit having three multiple branches which branches respectively include coils 74, 53 and 54. As coils 72 are thereby shunted, the effect of the circuit through coils 74 is to reverse the position of the armature of the local relay 52, whereby the branch of the line circuit through the point 78 is broken. As both said branches of the line circuit have already been tracedin their entirety further description of them is unnecessary at this point. It will be evident by reference to Fig. 4 (for the moment reading this figure with the armatures for the coils 53 and 54 attracted, the armature for the relay 52 being against the coils 72, and the contact 77 closed) thatthe coils 53 and 54 now hold their armatures by a divided circuit which passes through the contact 100 of the relay 54 and through the contact 98 of the relay 34, instead of through the coils 79) in the relay 52 as shown in Fig. 12, said divided circuit having three multiple branches which respectively include coils 74, 53 and 54, each. in series with the contact 98 just above referred to, until the following circuit for the coils 74 in the relay 52, shunting the coils 72, takes effect. This circuit is shown in detail in Fig. '13 and is as follows :-starting from the positive side of the generator 55, thence through portions of the wires 59 and 66, thence through the wire 75 to the coils 74 of the local relay 52, thence through the wire 76 and a portion of the wire 88, thence through a wire 99 to a contact 100 controlled by the armature of the local relay 54, thence through a wire 101 to the contact 98 and thence by way of a portion of the wire 65 back to the generator 55. This cir cuit shunts coil 7 2, moving armature of relay 52 from the position in which it is shown in Figs. 2 and 3, to the position in which it is shown in Fig. 4, the effect of which, of course, is to close the contact and open the contacts 7778. The opening of the contact 78 has no effect upon the line circuit because circuit is maintained through the contacts 42 and 44. The opening of the contact 77 breaks the local circuits for the coils of the local relays -5354 which then drop their armatures. The dropping of the armature of the local relay 54 closes the contact 61, and the circuit for the signal 22 is thereby closed. This circuit was described in detail in the fore part of the specification. It passes through the said contact 61, the contact 63 of the second line relay 45, and the contact 56 of the polarized track relay 34, deriving its energy from the generator 55. The home signal now moves to its clear position as is shown in Fig. 4. In other words, the group of the four alternate pulses in the track circuit has been completed, the various instruments have responded as a result thereof and hence the signal 22 moves to its clear position. It may be here noted that the movement of the signal 22 mechanically operates a pole changer 102, correspending to the pole changer 38 of the signal 24 in thenext block ahead, thereby completing a circuit whereby a distant signal at the entry of the :block' A can move to its clearposition, in the same manner as will presently be'described'in connection with the pole c'hanger'38'which, upon movement of the signal 24to its'clear'position by the derp'a rture of thetrain 58 from the block C,

completes a circuit whereby the distant signaras at the beginning of the block B can move to its clear position.

polarized-armature of the second line relay 45. vThe direction of the track circuit, however,'remains constant, that is to say, in the direction determined by the normal closed position of the pole changing armature of the line relay 28. The clearing of the distant signal 23 is controlled by the mechanical operation of'the pole changer 38 when the home'signal 24 clears, upon the train 58 leaving the block C and entering a block in "advance thereof. This eliects a reversal of the current, through the coils of the line relay 45, the circuit for which may be traced as follows: commencing at the positive side of the generator 36, thence through the wire '37 and the pole changer 38 (now closing its upper contacts), thence through the wire 47 to the coils of the second line relay 45, thence through the wire 46 to the contact point 44, thence through the wire 43 to the contact point 42, thence through the wire- 41 to the common line wire 40, thence through the wire 39 to thepole changer 38 (the position of which will be remembered is opposite to that shown in Fig. 4), thence through the wire 48 to the contact 49, thence through the wire 50 and the coils of the line relay 2 8, and the wire 51 to the generator 36. The operation of the line relay 45 will again efiect a reversal of the position of the polarized armature thereof, thereby establishing a circuit through a contact point 106 for operating the distant signal 23, but in 5 addition it may be noted that its neutral through the coils.

armature will be momentarily dropped and picked up again, this being the necessary consequence of the reversal of the current armature will momentarily open the contact 44 and this would open the line circuit but The dropping of the for the fact that there is another circuit in multiple therewith when the home signal is in its clear position as it is at this time, which circuit may be traced through a branch comprising a portion of the wire 97, a wire 103, to a circuit closer 104 mechanically operated by the home signal 22, thence through a wire 105 back to the wire 43 and thence on through the contact 42, so that when the home signal is clear the circuit closer 104 is in multiple with the contact 44 and will take its place when the contact 44 is open. It may be noted that though there was a momentary break in the line circuit through the coils of the relay 28 when the signal 24 moved to its clear position as just described, owing to the reversal of position of the pole changer 38, practice has demonstrated that the movement of the pole changer is so rapid that the coils of the relay 28 will not release their armature sufiiciently to allow it to reverse its contacts. The circuit for the distant signal, which as just stated, was closed through the contact point 106 is as follows: starting from the positive side of the generator 55, thence through portions of the wires 59 and 66, thence through a wire 107, to the contact point 106, thence through a wire 108 to the distant signal 23, thence through the wire 60 to the contact point 61 of the local relay 54, thence through the wire 62 to the contact 63 of the second line relay 45, thence through the wire 64 to the contact point 56 of the track relay 34, and thence through the wire 65 back to the generator 55. This circuit may be traced in Fig. 4, except that it must be noted that the polarized armature of the second line relay 45 will be in the opposite position to that in which it is shown in Fig. 4, this, of course, being due to the fact that the home signal 24 would be in its clear position as has been above described, and of course, as the result of the closing of the foregoing circuit the distant signal 23 will be in its oblique position instead of its horizontal position as shown in this figure.

\Vhile it ma be noted that at the moment of the reversal of the direction of: current through the coils of the second line relay 45, the neutral armature therefor was momentarily dropped and hence the signal circuit momentarily opened at the point 63, yet the duration of the break in the circuit will not be suiiicient to cause a change in the position of the signal 22, the usual slow acting means employed in such signals preventing the same from responding to such a momentary break. The break at contact point 63 is only momentary because the reverse current through relay 45 immediately picks up the neutral armature and closes the circuit at contact 63. The momentary break in the line circuit at contact 44 which takes place on this reversal of current through relay 45 has no effect because, during this momentary break, a path for the line circuit is provided around contact 44 through wires 97, 103, contact 104 and wire 105.

For ordinary purposes the pole changer 38 I employ is of the well known quick acting construction, the action of which is so rapid that the momentary opening of circuit between the contact points thereof during the pole changing movement, is immaterial, but should a slower moving pole changer be employed, 1 may provide a supplemental path for the current during the pole changing movement. I have shown such means in Fig. 4 of the drawings in which there is a circuit closing device 109 operated by movements of the signal and so operated just prior to the operation of the pole changer. This circuit closer has two stationary contact points 110-111, connected respectively with the fixed contacts of the pole changer, the movable circuit closing portions of the circuit closer 109 being connected respectively through relatively high resistances with the movable circuit closing portions of the said pole changer. The circuit closer 109 will be operated to close its contacts just prior to the time the pole changer in its operation will open circuit in moving from one of its sets of contacts to the other, but during this time the current will be permitted to flow through the path established by the circuit closer 109. Directly, however, the movement of the pole changer is completed and the new path is established, the path established by the circuit closer 109, while still complete, will be shunted owing to the resistances therein.

The foregoing is a complete description of the various steps necessary before a'signal can move to its clear position; briefly summarized these steps are as follows: Starting with the train on the block B the polarized armature of the track relay 84 is in its position to the right, as shown in the drawings, closing the contact 56. When the train leaves the block B and enters the block C then this polarized armature makes its first movement to the left; this operates the local relay 52 causing the coils thereof 72 to attract their armature which moves to the left. This completes a line circuit through one of its contacts 7 8 and the contact 80 of the local relay 53. This causes the polarized armature of the track relay 34 to make its first movement to the right. This latter movement energizes the coils of the local relay 53 thereby breaking the line circuit at the contact point 80; thereupon, the polarized armature of the track relay makes its second movement to the left with the result that the coils of the local relay 54 are energized, the coils 53 still remaining energized. The energizing of the coils of the local relay 54 completes a line circuit, this time through coils of the second line relay 45; simultaneously, the polarized armature of the track relay 84 makes its second movement to the right and its neutral armature closes a line circuit through the contact point 42 and the contact point 44 closed by the operation of the second line relay 45 despite the opening of the other path of the line circuit through the points 78 and 96. The return movement of the armature of the local relay 52, resulting from the lifting of the neutral armature of the track relay 34, opens the cirsuit for both of the local relays 53 and 54, and thereupon the circuit for the signal 22 is completed through the contact 61 of the local relay 54, and the signal 22 moves to its clear position. Line circuit is now permanently closed through the line relays 45 and 28. The track circuit is permanently closed through the polarized track relay 84 and current flows in a direction which causes the polarized armature of the relay 34 to close the contact 56 and the four reversals in the track circuit required by the system having taken place, the neutral armature is attracted and remains attracted until another train enters the block B.

It must be noted that there is a slow release period in the instrument 52, that is to say, after the coils 72 have been shunted the coils 72 will not release their armature until after a predetermined interval of time, the same being due to the residual charge in the winding of the coils 72 and to the fact that the armature for the coils 72 is allowed to come into metallic contact with the cores thereof. Another cause for this residual charge in and slow release of magnet 72 is due to the fact that the circuit of magnet 72 is not actually disrupted during the slow release period of the magnet, the magnet being merely shunted and thereby left in a metallic circuit from which the current gradually subsides. The period of this slow release will be determined by the position of the coils 74 with respect to the armature and may be regulated by an adjustment thereof, an increase of such period being, of course, efiected by the adjustment of the coils 74 a farther distance away from their armature. In the present instance a period of, say, three seconds may be selected, though other predetermined periods may be employed as is desired. It will, of course, be understood that a slow release period may be effected by other means than that shown, but the means shown is a preferred form in that in practice I have found it to be very efiective for the purpose.

Because of this slow release period which commences when the second pulse in the track circuit effects the closing of the contact 56 the circuit for the coils 74 via the contacts 8785'56 in parallel with the circuit I for the colls 53 via the contacts 778556 7 as shown in Fig. 8 will fail to. cause the coils 74 to immediately move the armature awayfrom the coils 72. This gives time for the armature of the line relay 28 to drop to b'ring'about the third pulse in the track circuit, and thereby to open the contact 56. Then, by the circuit for the coils 74 in parallel with the coils 53 via the coils 72 as clearly shown in Fig. 8, the condition of slow release'for the armature of the coils 7 2 is reestablished. The third pulse in the track circuit closes the contact 57 then again 'because'of the slow release period of the to bring aboutthe fourth and last pulserequired in the track circuit, and thereby'to open the contact 57. Then by the circuit in parallel with the coils 53 and 54 through the coils 7 2 as clearly shown in Fig. 12 the condition of slow release of the armature by the coils 72 is reestablished.

The result of'the fourth pulse in the track circuit is that the track relay 34 closes the contact 56, and also by the lift of the neutral armaturecloses the contact 98, completing-a circuit for the coils 74 and shunting the tacts 7 7112100-98.

the coils 72 after their circuit has coils 72 as clearly shown in Fig. 13. Prior to the coils 7 4 attracting their armature by reason of the'circuit completed therethrough and shunting coils 7 2 as just described, and which-in Fig. 4 they are shown to have done, the'armatures for the coils 53 will be in their attracted position and therefore the coils 53 will be in parallel with the coils 74 through the contacts.778710098 and the (30118 54 will also be in parallel through the con- The coils 5354 therefore continue to hold their armatures until the contact 77 is opened by the fact that the coils 74 gradually overcome the remaining power in the shunted coils 72 due to the residual charge and closed magnetic circuit therein. It may be noted at this point that the magnetic circuit referred to is formed by the armature of the instrument 52 coming into direct contact with the cores of the coils 72, the iron to iron contact thus formed completing the circuit. The residual charge is that remaining in the windin 's of een opened. After the armature of the instrument 52 has been pulled away from the coils 72 the relay52 is in the position shown in Fig. 4. The relays 53 and 54 as their circuits are now open at the contact 77, are also in the position shown in Fig. 4 and the home signal 22 moves to its clear position as shown in this figure.

The foregoing is then a complete description of a normally clear signal system operated in accordance with my invention, and I will now show how it is that such a system gives protection against the inroads of for eign currents.

First, it will be noted that it is fundamental to the system described in the foregoing that a predetermined number of pulses in their required order,that is to say, in the specific embodiment of my invention herein,-four pulses, two in one direction and two in the other, and in alternate order,- must be produced before the signal can clear, and this, of course, is such an unlikely condition to arise from foreign current that it may, for all practical purposes, be said to be inconceivable, but it will be noted that in addition to the foregoing, these pulses must not only be produced in the order and sequence named, but the last two must be produced within the predetermined periods of time demanded by the slow release instruments 52. For instance, supposing a foreign current were to enter the track circuit and bring about the second pulse, it would be necessary for it to again reverse within 7 the slow release period of the instrument 52 and then again reverse within th1s slow,

period and then remain reversed in order for the signal to clear. Assuming that the foreign current did enter the track circuit to bring about the first pulse and then reverse so as to bring about the second pulse closing the contact 56 and failed to reverse so as to bring about the third pulse within the slow release period of the instrument 52, then the coils 74 would pull over the armature of'the instrument 52, breaking the circuit for the coils of the local relay 53 at the point 77, thereby necessitating the re-commencement of the group of pulses, or, in other words, the entry of a new first pulse followed by the second, third, and fourth pulses in the required order and in the required period of time. Therefore for a foreign current to operate the system it must first enter the track circuit in the direction to cause the polar armature of the relay 34 to close the 4 simplicity of illustration I have shown the system .as applied to signals normally clear. In this system the pulses continue for as long a time as it takes the signal to clear in stead of being limited to a predetermined number as in the systems above described.

In Fig. 15 the parts are shown in their normal positions with no train'within two blocks of those shown, while in Fig. 14 the parts are shown with the train in the block I. The drawings illustrate one complete block H and a portion of the blocks G and I to the rear and in advance thereof. Home and distant signals 22 and 23 are arranged at the entry end of the block H and similar home and distant signals 22 and 23 are arranged at the entry end of the block I. The home signal 22 is provided with a pole changer 140 and a circuit closer 141 while the home signal 522 is similarly provided with a pole changer 142'and a circuit closer similar to the circuit closer 141 (not shown). For each block of the system there is included a line relay 143, corresponding to the line relay 28 of the other system, a second line relay 144 having a polarized and neutral armature, the same corresponding to the second line relay 45 of the other system, a track relay 145 in place of the track relay 34 of the other system, the track relay 145 being of the un-polarized type as distinguished from the polarized type of track relay used in the other system, a local relay 146 for a primary signal circuit, and a transformer 147, the secondary winding of which is connected with the coils of the relay 146. There are also two generators 148149 for supplying current for the line circuits, for the primary winding of the transformer, and for the signal circuits; and there is a generator 150 for supplying current to the track circuit.

The manner in which the various instruments are connected will be best understood by a description of the operation thereof. I will now proceed to such description, having particular reference to Fig. 14 in which the train is shown as in the block I. When the train entered the block H from the block G the shunting of the coils of the track relay 145 resulted in the dropping of their armature and the consequent opening of the signal circuits at the contact point 175, caus ing the signals 22 23 to 'go to danger. The movement to danger of the signal 22 opened the circuit closer 141, thereby opening the line circuit, thereby deenergizing the line relay 144. The circuit for the line relay 143 is closed, however, through a back contact 151 controlled by the armature of the track relay 145. llow, when the train leaves the block H and enters the block I the track relay 145 will be energized from the generator 150 and its armature attracted. This will break the line circuit for the coils of the line relay 143 at the contact point 151 thereby causing the armature of the line relay 143 to drop its armature and pulsations will be set up in the track circuit in the following manner: The armature of the line relay 143 is a pole changing armature, operating between contacts which reverse the direction of current from the generator 150 in the track circuit. This produces corresponding pulses in the coils of the track relay 145, thereby causing it to .alternately drop and attract its armature, thereby alternately making and breaking circuit at the points 175151. The circuit opened and closed at the point 151 is a line circuit which may be traced as follows: starting from the positive side of the generator 149, thence through a wire 152 to the coils of the line relay 143, thence through a wire 153 to one of the points of the pole changer 142, thence through a wire 154 through a circuit closer 155 and a wire 156 to the contact point 151 of the track relay 145', thence through a wire 157 to the common line wire 158, thence through a wire 159 back to the pole changer 142, and thence through a wire 160 back to the generator 149. When the circuit is complete through the line circuit just described. the coils of the line relay 143 are energized and its armature is raised. During the movement, however, of the armature from its lowermost to its uppermost position there is no circuit completed for the coils of the track relay 145; hence its armature remains down and the contact 151 remains closed. When, however, the armature of the line relay 143 reaches its uppermost position it completes the track relay circuit again and the track relay coils attract their armature to thereby break the line circuit at the point 151. The coils of the line relay 143 now become deenergized allowing their armatures to drop and directly their armature commences to so drop the track circuit will be broken and the coils of the track relay will drop their armature. The line circuit will now be again closed through the contact point 151, and the armature of the line relay 143 will again be lifted and so on. These reciprocations of the armatures of the instruments 143 and 145 continue in this manner until the line circuit for the relay 143 is permanently closed at another point by the operation of the signal as will presently be shown.

The reciprocations of the track relay 145 in addition to making and breaking circuit at the contact point 151 also makes and breaks circuit at the contact point 175 as has been stated and the circuit thereby made and broken may be traced as follows: starting from the positive side of the generator 148, thence through a wire 161 to the pri: mary winding of the transformer 147; thence through a wire 1.62 to a back contact con- 

